Ultrasonic tweezer for multifunctional droplet manipulation

Area of Science:

• Acoustic manipulation
• Microfluidics
• Surface science

Background:

• Contactless droplet manipulation is crucial for applications like thermal management and water harvesting.
• Current methods face challenges in response speed and adaptability, often requiring surface or droplet pretreatment.

Purpose of the Study:

• To propose a versatile droplet manipulation system using a phased array droplet ultrasonic tweezer (DUT).
• To demonstrate precise, programmable control of droplets without pretreatment.

Main Methods:

• Development of a droplet ultrasonic tweezer (DUT) utilizing a phased array.
• Generation of a twin trap ultrasonic field for droplet trapping and maneuvering.
• Utilizing acoustic radiation force for droplet manipulation.

Main Results:

• The DUT achieved flexible and precise programmable control by repositioning the ultrasonic focal point.
• Demonstrated droplet manipulation through a confined slit (2.5x smaller than droplet size).
• Showcased droplet traversal of steep inclines (up to 80°) and vertical reciprocation.

Conclusions:

• The proposed DUT offers a robust paradigm for contactless droplet manipulation.
• The technology enables versatile applications including droplet ejection, dispensing, and surface cleaning.